Column: A dangerous confluence on the California coast: beach erosion and sea level rise

Bob Guza, a researcher at U.C. San Diego’s Scripps Center for Coastal Studies, says California beaches are threatened due to sand shortage.


Bob Guza has the best job in California.

That’s just my opinion, but take a look at this deal:

At 68, his work clothes are a ball cap, shorts and flip-flops. He sets his own hours and gets paid to hang out on the beach all day with his toys, which include a sand buggy, a jet ski and a drone. Guza retired in 2012, but after a month off, the professor emeritus couldn’t think of anything better to do with his time, so he went back to work.

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“I’m a lucky guy,” says the researcher at UC San Diego’s Scripps Center for Coastal Studies.


I met Guza at the Scripps pier, where his office hovers over the beach. Guza calls his operation the beach and sand lab, and he and his team of seven study the movement of sand along the California coast.

This is not child’s play, despite the toys and Guza’s youthful exuberance. Two things are happening simultaneously along the coast, Guza explained, and it’s critical that we know more about each of them.

One is beach erosion, the other is sea level rise.

If we do nothing, absolutely nothing, I’d say in 50 years we’re going to have very few beaches left.

— Bob Guza

The risk is that from the Oregon to Mexican borders, California beach communities, homes, businesses and multibillion-dollar recreation and tourism industries could get swamped.

“I’ll tell you what happens if beaches are not sandy,” said Guza, who speaks in a fantastic Philly accent and gets so excited, he seems on the verge of hyperventilating. “Tourists do not come. The Germans will not pay to sit on rocks.”

This is not going to happen next year or in the next decade, said the sand man. But it’s going to happen.

“If we do nothing, absolutely nothing, I’d say in 50 years we’re going to have very few beaches left,” he said. “They’re going to be narrow. Maybe it’ll be 75 years. But we’re looking down the barrel. Sea level is going to rise ... and the only thing the beaches can do is shrink.”

So what can we do about it?

First, understand the science and the impact of our giant human footprint on the coast.

Beaches erode because of wave action and storms. Depending on conditions and seasons, they can restore themselves. But there’s a sand deficit on Southern California beaches, Guza said, because we’ve cut off sediment flow.

Here’s how Guza explains it, flabbergasted by his own summary:

Act One: “Shopping center is built in flood plain. Flood plain floods. Shock and amazement. Flood plain floods a second time. Need for action. Rivers are dammed.”


Act Two: “Build close to cliff’s edge that has historically eroded. But build close to cliff’s edge anyway. Then, when cliff erodes, express shock. Take action. Build sea wall. Repeat. Forty percent of the cliffs in San Diego County are now armored.”

What to do?

First, assess the damage. Guza and his team use GPS equipment mounted on the sand buggy and jet ski to seasonally map beach levels and the impact of tides and storms. Last week, Guza introduced me to one of his former post-doc students, Timu Gallien, who was test-driving a drone that will simplify the mapping of beach levels at Torrey Pines -- technology that could be put to use up and down California’s 1,100-mile coast. If a road is threatened or a development proposed, beach erosion history will make for smarter planning.

Bob Guza and his research team use GPS equipment mounted on a sand buggy and jet ski, above, to seasonally map beach levels and the impact of tides and storms.
Bob Guza and his research team use GPS equipment mounted on a sand buggy and jet ski, above, to seasonally map beach levels and the impact of tides and storms.
(Allen J. Schaben / Los Angeles Times )

This is “critical if we want to understand our future vulnerabilities,” said Gallien. She is a coastal flooding expert now teaching at UCLA, but still collaborating with Guza, whom she called an international giant in his field.

Guza showed me a photo Gallien took last fall when El Niño took a bite out of the beach at Torrey Pines, up to the shoulder of the highway. Just up the road, the highway and Amtrak line come together, precariously close to another section of eroding beach.

One thing you can do to protect homes and infrastructure is dump more sand on the beach, Guza said, and millions have been spent in California on that very thing. But you can’t just willy-nilly drop a dune on a beach and assume that will work, Guza said. Sometimes it does, sometimes it doesn’t, and more research is needed to know the whys and wherefores.


Guza’s team studied a sand-nourishment project in Imperial Beach, where hundreds of thousands of cubic yards of sand were dredged from the ocean and dumped in front of homes that were built way too close to the water. Residents sued when some seawater got through anyway. Then, gradually, some of the sand moved south and blocked the mouth of the Tijuana Estuary this year when El Nino wave action complicated matters.

When it rained, sewage from Tijuana turned the estuary into a clogged toilet, killing off fish.

“There was a massive die-off of leopard sharks,” said Imperial Beach Mayor Serge Dedina, who joined me and Guza on a tour of the site.

Dedina has already begun planning for the impact of sea level rise and said every coastal community in the state has to do the same. In Imperial Beach, Dedina said, restoring coastal wetlands will make them better able to absorb storm water, and it may turn out that moving threatened buildings inland is cheaper and smarter than trying to save them with sea walls or piles of sand.

The California Coastal Commission is in the midst of a statewide assessment, working with local communities to identify high-risk areas.

As I’ve noted often in my summer-long road trip that began on the Oregon border, we love the water a little too much in California, and although the 40-year-old Coastal Act has stymied dozens of beachfront projects, we’ve foolishly allowed too much development — much of it preceding the Coastal Act — too close to the sea.


In parts of Northern California, including San Francisco and Humboldt Bay, the Pacific Coast Highway and Highway 101 flood every now and then.

Here and there in Southern California, the beach is now the highway’s shoulder.

And in Malibu, wealthy landowners have invested in rock and sandbags to hold back the sea.

Professor Guza is a scientist, not a politician, so he’s reluctant to give policy advice. But he says El Nino could become the norm in 20 or 30 years, and sea level rise is hard to predict but sure to visit us.

“There are management strategies,” he said, “but we have to learn as we go” and make tough decisions on the cost of protecting roads, rail lines and buildings versus the cost of waiting to see what happens.

“Doing nothing,” said Guza, “is making a decision — the decision that we don’t need sandy beaches in California.” | Follow on Twitter: @LATstevelopez


Weigh in at @JerryBrownGov #SaveYourCoast and (916 445-2841) or email


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